This project is on the development of cellular slime molds where it is known from previous work that cyclic AMP plays a significant role. We are pursuing two aspects; its role in chemotaxis and in differentiation. We have purified a new chemoattractant for a species that is not attracted by cyclic AMP and we would like to identify it chemically and study its relationship to cyclic AMP activities. In the differentiation study we plan to study the role of cyclic AMP phosphodiesterase in controlling the interphase period between feeding and aggregation. We are also studying, using a new method, the factors which affect the spore/stalk ratios. BIBLIOGRAPHIC REFERENCES: Machac, M.A. and J. T. Bonner. Evidence for a sex hormone in Dictyostelium discoideum. J. Bact. (in press - January 1976 issue). Pan, P., E. M. Hall and J. T. Bonner. Determination of the active portion of the folic acid molecule in cellular slime mold chemotaxis. J. Bact. 122: 185-191, 1975.